In this article, Josef Vachek provides an overview of the notion of "dynamism", as it was articulated in some of the major works during the classic period of Prague school functionalism. The chapter summarizes the understanding of dynamism as the non-static nature of language and explains the therapeutic effect which the dynamism of language has in respect to the language system as such. The chapter attests to the sensitive combination of the synchronic and diachronic approaches among early scholars of the discipline. This is based on their conviction that the two levels of analysis can hardly be separated in efforts to understand the complex systematic nature of language: the current state of the language is systematically being explained as a result of past developments.